Cystic fibrosis (CF) is a genetic disorder caused by a mutation in the CFTR gene, affecting systems like the lungs and digestive tract. Medical advancements have increased the life expectancy for men with CF, making reproductive health an important consideration. The disorder profoundly impacts male fertility, raising the question of whether a man with CF can conceive naturally.
Cystic Fibrosis and Male Fertility: The Biological Reality
The overwhelming majority of men with cystic fibrosis, approximately 95% to 98%, are unable to conceive a child through natural sexual intercourse. This high rate of infertility is not due to a failure to produce sperm but rather a physical blockage in the reproductive tract. The underlying cause is a condition called Congenital Bilateral Absence of the Vas Deferens (CBAVD).
The vas deferens is a tube that transports mature sperm from the epididymis, where they are stored, to the ejaculatory duct. In men with CF, the malfunctioning CFTR protein prevents the normal development of the vas deferens, leading to its absence or atrophy early in embryonic development. This congenital absence means there is no pathway for the sperm to exit the body during ejaculation.
This results in obstructive azoospermia, a condition where no sperm are present in the ejaculate. The testes typically continue to produce healthy sperm, but the sperm are trapped, making natural conception impossible.
Modern Solutions for Conception
Despite the barrier caused by CBAVD, men with cystic fibrosis can become biological fathers through the use of Assisted Reproductive Technologies (ART). Since sperm production is usually normal, medical intervention focuses on retrieving the sperm and facilitating fertilization. This approach has transformed biological parenthood from an unattainable goal into a realistic outcome for most couples.
The process begins with surgical sperm retrieval (SSR), a minor outpatient procedure performed by a urologist. Techniques such as Percutaneous Epididymal Sperm Aspiration (PESA) or Testicular Sperm Extraction (TESE) are used to collect sperm directly from the epididymis or the testicle. Viable sperm is successfully recovered in nearly all cases, with studies showing a success rate of over 98% for retrieval.
The retrieved sperm is then combined with the female partner’s egg through a highly specialized laboratory technique called Intracytoplasmic Sperm Injection (ICSI). ICSI involves injecting a single, healthy sperm directly into the center of a mature egg, which then facilitates fertilization. This fertilized egg is then allowed to develop into an embryo before being transferred to the woman’s uterus through In Vitro Fertilization (IVF).
This combination of SSR, ICSI, and IVF has a high success rate. One large study showed that 84% of couples who proceeded with ICSI achieved a live birth. These advancements effectively bypass the physical obstruction, providing a viable path to genetic parenthood for men with CF.
Understanding Genetic Transmission Risks
When a man with cystic fibrosis uses ART to conceive, every child will necessarily inherit one mutated copy of the CFTR gene from him. Whether the child develops CF or is merely a carrier depends entirely on the genetic status of the female partner.
Genetic counseling and carrier screening for the female partner are mandatory steps before attempting conception. The partner will be tested to determine if she is also a carrier of a CFTR gene mutation. If the female partner is not a carrier, the child will inherit one mutation from the father and one normal gene from the mother, meaning the child will be a carrier but will not have CF.
If the female partner is a carrier, the genetic risk changes significantly. The child has a 50% chance of inheriting the mutated gene from both parents and developing CF. The child also has a 50% chance of being a carrier, inheriting the mutation from the father and the normal gene from the mother.
For couples where the female partner is a carrier, Preimplantation Genetic Diagnosis (PGD) can be used during the IVF process. PGD is a technique that screens the embryos for the CF-causing gene mutations before implantation. This allows the couple to select an embryo that is either a carrier or is genetically unaffected, significantly reducing the risk of the child inheriting the disease.